Spark plug



April 26,.1932.

N. SPINELLII SPARK PLUG Filed May 19 1930 jvzcozmSfl/vzw INVENTORATTORNIY Patented Apr. 26, 1932 UNITED STATES PATENT OFFICE NICOLASPINEL-LI, OF NEW YORK, N. Y., ASSIGNOB OF ONE-HALF 1'0 CARLO DALESSIO,

' OF NEW YQRK, N. Y.

SPARK PLUG Application filed May 19,

This invention relates to spark plugs, and the principal object thereofis to provide a new and improved spark plug having, at once, theadvantages of includlng a readily attachable central electrode, ofexhibiting high compression holding qualities under all conditions, andof incorporating comparatively few and relatively inexpensive parts.

Other'objects and advantages of the invenm tionwill be hereinafterspecifically pointed out, or will become apparent, as the specificationproceeds.

With the above indicated objects in view,

the invention resides in certain novel constructions and combinationsand arrangement of parts, clearly described in the followingspecification and fully illustrated in the accompanying drawings, whichlatter show an embodiment of the invention as at present preferred.

In said drawings:

Fig. 1-is, on rather a large scale, an axial section of said embodiment,with the two electrodes, however, in elevation;

Fig. 2 shows the center electrode, exactly as seen in Fig. 1, but alone;

Fig. 3 shows, partially in axial section, and partially in elevation, ametal sleeve, for coacting with said center electrode as indicated inFig. 1; and

Fig. 4 is an axial sectional view, partly in elevation of the metalbushing which cooperates with the sleeve and electrode.

Similar reference characters refer to similar parts throughout theseveral view of the drawings.

Referring now more in detail to the embodiment illustrated in saiddrawings, the spark plug of the present invention preferably includes,as is well known in the art, a metal shell 6, and an electrode 7 carriedthereby, a core 8 of porcelain or the like for sleeving the centerelectrode, hereinafter to be more particularly described, gaskets 9 and9a, and a nut 11; such nut externally threaded and screwed into theupper internally threaded portion 6' of the shell, for compressing thegaskets 9 and 9a and thereby clamping the porcelain core within theshell, tightly and in a manner to avoid compression leakage and 1930.Serial No. 453,785.

yet without danger of cracking of fracturing the core.

Said shell 6 may, externally, be of conventional shape, and willdesirably include a wrench head as indicated at 6 and an external screwthread 6a, whereby in the usual way the spark plug may be mounted on thecylinder head or other supporting body.

The core 8, in the present case, has a lower most narrow cylindricalbore 10; and above this bore 10 is a bore 10d of large enough diameterto receive the bushing 12 next to be described,this bore 106 beinginternally threaded down through almost its entire length asillustrated.

The bushing 12 (Fig. 4) is of metal and has an external thread 106matching the internal thread in bore 10d of the porcelain core. The bore13a of the bushing 12 is rounded spherically as indicated at 12' nearits bottom, and below this rounded seat 12 said bore is continued as alesser bore 12". The main or upper bore of the bushing 12 is internallythreaded, from its top down slightly more than half way of its length,as indicated at 13. The bushing 12 has a head 12a provided with a cup120 having a plane bottom perpendicular to the cylindrical inner wall ofthe cup side In this instance the bushing bore portion 13 is adapted toreceive a threaded sleeve 18, into which sleeve 18 the upper threadedend 15a of the center electrode 15 has been previously threaded thesleeve 18 having a bore 150 including an in ternally threaded portion15?) for this purpose. V

The center electrode 15, which is of course of metal and preferablyintegral from end to end, incorporates midway of its ength a sphere 14c,of the same diameter as the rounded seat 12 in the bottom of bushing 12;and the said electrode also includes, below the sphere 14 an elongatedportion 17 acting asv a sparking end of the center electrode; and thisportion 17 is cylindrical, like the portion 170: at the opposite side ofthe sphere 14.

As the parts are shown assembled, the end 17 of the center electrodeacts as the s arking end of that electrode and protrudes elow (ill thelower end of core 10, in sparking position relative to the adjacent endof electrode 7. It will be noted that the threaded portion 15a of thecenter electrode has been screwed up into the threaded portion 15b ofthe sleeve 18. This has seated the sphere 14 in the rounded portion 12aof sleeve 18. The sleeve 18 is then threaded into the bore 13 of bushing12 so that the sphere 14 seats in the rounded bottom of bushing 12. Allthe parts are nicely machined and to an ex tent such that anycompression leak along the lengths of any of the bores for the centerelectrode will be absolutely stopped by the clamping together tightly ofthe parts 14, 12a and 12.

The spark plug is completed, for the attachment of a conductor in thefamiliar way to a threaded terminal 18 constituting the upper end of themetal sleeve 18, the sleeve terminal 18 being provided with a lock nut18a. This lock nut 18a cooperates with a nut 185 provided at the upperend of the sleeve 18 for this latter purpose. Also, the

nut 18 is preferably polygonal in "form, for

manipulation by a wrench or the like in securing the sleeve in place;and, as seen in Fig. 1, the nut 185 seats in the cup portion 12a of thebushing 12 when the parts are assembled,

When the center electrode is to be replaced, it is merely necessary tounscrew and remove the sleeve 18, and rein-sert a new center electrode,and screw the sleeve down into place again within the bushing 12.

The hereinbefore described construction admits of considerablemodification without departing -from the invention; therefore, it is thewish not to be limited to the precise arrangements shown and described,which are as aforesaid, by way of illustration merely. In other words,the scope of protection contemplated is to be taken solely from theappended claims, interpreted as broadly as is consistent with the priorart.

What is claimed as new'is:

1. In a spark plug, the combination with a shell, an insulator, andmeans -for securing said insulator within the shell, oi a centerelectrode having a spherical enlargement intermediate its ends, and amounting therefor in said insulator, said mounting including a bushinghaving a rounded seat to lit against one portion of said sphericalenlargement,

signature.

NICOLA SPINELLI.

